Fix bug in prt_backtrace (treat case where syms is NULL)
Fix bug in prt_backtrace (treat case where syms is NULL)

shujingke/opencog,Selameab/opencog,gavrieltal/opencog,rohit12/atomspace,anitzkin/opencog,williampma/atomspace,inflector/opencog,jlegendary/opencog,ruiting/opencog,gaapt/opencog,printedheart/opencog,virneo/atomspace,kinoc/opencog,eddiemonroe/atomspace,inflector/atomspace,eddiemonroe/opencog,eddiemonroe/opencog,ruiting/opencog,ruiting/opencog,kinoc/opencog,ruiting/opencog,Selameab/opencog,tim777z/opencog,ArvinPan/opencog,anitzkin/opencog,cosmoharrigan/atomspace,ArvinPan/opencog,inflector/opencog,cosmoharrigan/opencog,shujingke/opencog,sanuj/opencog,rohit12/opencog,roselleebarle04/opencog,jswiergo/atomspace,cosmoharrigan/atomspace,prateeksaxena2809/opencog,TheNameIsNigel/opencog,rohit12/opencog,Allend575/opencog,yantrabuddhi/atomspace,williampma/opencog,eddiemonroe/opencog,Allend575/opencog,gaapt/opencog,printedheart/opencog,AmeBel/atomspace,sanuj/opencog,williampma/opencog,jlegendary/opencog,andre-senna/opencog,yantrabuddhi/atomspace,kinoc/opencog,cosmoharrigan/atomspace,Tiggels/opencog,ArvinPan/opencog,rodsol/opencog,printedheart/opencog,rohit12/atomspace,kim135797531/opencog,rTreutlein/atomspace,virneo/atomspace,printedheart/opencog,shujingke/opencog,iAMr00t/opencog,williampma/opencog,Tiggels/opencog,ceefour/opencog,ruiting/opencog,yantrabuddhi/opencog,kim135797531/opencog,Selameab/atomspace,inflector/atomspace,Selameab/atomspace,tim777z/opencog,ceefour/atomspace,iAMr00t/opencog,andre-senna/opencog,rodsol/opencog,rohit12/atomspace,UIKit0/atomspace,prateeksaxena2809/opencog,virneo/opencog,eddiemonroe/atomspace,kim135797531/opencog,misgeatgit/opencog,prateeksaxena2809/opencog,williampma/opencog,misgeatgit/atomspace,misgeatgit/opencog,williampma/atomspace,prateeksaxena2809/opencog,inflector/opencog,ceefour/opencog,anitzkin/opencog,Allend575/opencog,roselleebarle04/opencog,sumitsourabh/opencog,Tiggels/opencog,yantrabuddhi/atomspace,eddiemonroe/atomspace,prateeksaxena2809/opencog,printedheart/atomspace,ArvinPan/atomspace,anitzkin/opencog,iAMr00t/opencog,rTreutlein/atomspace,shujingke/opencog,cosmoharrigan/atomspace,inflector/opencog,ArvinPan/atomspace,andre-senna/opencog,eddiemonroe/opencog,misgeatgit/atomspace,andre-senna/opencog,Tiggels/opencog,ceefour/opencog,misgeatgit/atomspace,ceefour/atomspace,ceefour/atomspace,UIKit0/atomspace,gavrieltal/opencog,andre-senna/opencog,anitzkin/opencog,yantrabuddhi/opencog,misgeatgit/atomspace,Allend575/opencog,shujingke/opencog,TheNameIsNigel/opencog,Selameab/atomspace,roselleebarle04/opencog,MarcosPividori/atomspace,rodsol/opencog,kim135797531/opencog,sumitsourabh/opencog,prateeksaxena2809/opencog,Tiggels/opencog,kim135797531/opencog,gavrieltal/opencog,rodsol/atomspace,printedheart/atomspace,ceefour/opencog,misgeatgit/opencog,rTreutlein/atomspace,cosmoharrigan/opencog,gaapt/opencog,williampma/opencog,tim777z/opencog,virneo/opencog,gavrieltal/opencog,virneo/opencog,AmeBel/atomspace,AmeBel/opencog,sanuj/opencog,williampma/atomspace,UIKit0/atomspace,MarcosPividori/atomspace,roselleebarle04/opencog,sumitsourabh/opencog,kinoc/opencog,Selameab/opencog,AmeBel/opencog,rodsol/atomspace,MarcosPividori/atomspace,iAMr00t/opencog,andre-senna/opencog,williampma/opencog,inflector/opencog,virneo/opencog,yantrabuddhi/opencog,virneo/opencog,kinoc/opencog,UIKit0/atomspace,ArvinPan/opencog,MarcosPividori/atomspace,ruiting/opencog,roselleebarle04/opencog,virneo/opencog,Allend575/opencog,yantrabuddhi/atomspace,williampma/atomspace,eddiemonroe/atomspace,rohit12/atomspace,printedheart/opencog,TheNameIsNigel/opencog,eddiemonroe/opencog,jlegendary/opencog,yantrabuddhi/atomspace,yantrabuddhi/opencog,rodsol/atomspace,sumitsourabh/opencog,inflector/opencog,tim777z/opencog,virneo/atomspace,gavrieltal/opencog,yantrabuddhi/opencog,rTreutlein/atomspace,AmeBel/opencog,roselleebarle04/opencog,misgeatgit/opencog,rTreutlein/atomspace,cosmoharrigan/opencog,AmeBel/opencog,shujingke/opencog,AmeBel/atomspace,ArvinPan/atomspace,virneo/opencog,Selameab/opencog,Selameab/opencog,TheNameIsNigel/opencog,gaapt/opencog,kinoc/opencog,TheNameIsNigel/opencog,roselleebarle04/opencog,eddiemonroe/atomspace,misgeatgit/opencog,anitzkin/opencog,ceefour/atomspace,gavrieltal/opencog,gavrieltal/opencog,rohit12/opencog,shujingke/opencog,virneo/atomspace,printedheart/opencog,misgeatgit/atomspace,eddiemonroe/opencog,cosmoharrigan/opencog,rodsol/opencog,ArvinPan/atomspace,jlegendary/opencog,TheNameIsNigel/opencog,jlegendary/opencog,ruiting/opencog,AmeBel/opencog,Allend575/opencog,eddiemonroe/opencog,yantrabuddhi/opencog,yantrabuddhi/opencog,Selameab/opencog,sanuj/opencog,rohit12/opencog,misgeatgit/opencog,sanuj/opencog,jswiergo/atomspace,Selameab/atomspace,inflector/atomspace,gaapt/opencog,jlegendary/opencog,ArvinPan/opencog,ceefour/opencog,ceefour/opencog,kinoc/opencog,inflector/atomspace,printedheart/atomspace,sumitsourabh/opencog,cosmoharrigan/opencog,iAMr00t/opencog,ArvinPan/opencog,inflector/atomspace,Tiggels/opencog,inflector/opencog,AmeBel/atomspace,rodsol/opencog,tim777z/opencog,rohit12/opencog,rohit12/opencog,sumitsourabh/opencog,jswiergo/atomspace,AmeBel/opencog,AmeBel/opencog,cosmoharrigan/opencog,tim777z/opencog,iAMr00t/opencog,misgeatgit/opencog,misgeatgit/opencog,jswiergo/atomspace,ceefour/opencog,rodsol/opencog,gaapt/opencog,Allend575/opencog,andre-senna/opencog,gaapt/opencog,anitzkin/opencog,jlegendary/opencog,rodsol/atomspace,inflector/opencog,printedheart/atomspace,sanuj/opencog,AmeBel/atomspace,sumitsourabh/opencog,misgeatgit/opencog,kim135797531/opencog,prateeksaxena2809/opencog,kim135797531/opencog